There's a flurry of tweets and a petition currently making rounds on the internet asking Vodafone to pay its taxes. That's the £4.8bn of tax that HM Revenue & Customs boss Dave Hartnett allegedly let Vodafone forgo when settling a longstanding tax dispute with the company. The dispute started in 2000, when Vodafone acquired German engineering company and mobile phone operator Mannesmann, in what was at the time the biggest takeover ever.

The details of this case are complex. Not all, of course, are in the public domain. Whether or not £6bn of tax was in total owed or not will never really be known. But what seems much more likely is that Vodafone had expected to pay much more than the £1.2bn it will finally settle. Reports suggest that they had put aside at least £2.2bn to cover the payment and they must, as a result, be laughing all the way to the bank.

I do, however, have sorry news for those who want Vodafone to pay up: if HMRC have really settled the case then the matter is done and dusted, and the opportunity to charge will have gone. This does not change the fact that this affair leaves a sour taste in the mouth, not least because days after it was announced, George Osborne was promoting Vodafone in India – a visit that must have been agreed before the tax announcement was made on 23 July. Of course, the coincidental timing may just be fortuitous and no one is suggesting Vodafone has done anything wrong, but the impression given is that HMRC rushed a deal through before the Indian visit.

If they did, that seems consistent with what many see as the "business friendly" and even "tax-haven friendly" attitude that seems to pervade our tax authority, especially faced with companies who openly admit they seek to minimise tax in any way they can – as Vodafone does when it says: "The maximisation of shareholder value will generally involve the minimisation of taxation."

But is that something HMRC and our treasury should accept? I have estimated UK companies avoid at least £12bn in tax a year – in no small part, I am quite sure, by the use of tax haven operations, which is widespread. When I and others surveyed the FTSE 100 companies last year, we found that only 33 published a list of where all their subsidiary companies are – although it is a legal requirement for all of them to do so. And without exception, those who did report had tax haven subsidiaries – using the definition established by the Tax Justice Network – with an average of 79 each.

This suggests something worrying. There seems to be a widespread dedication to using these places – so many of which are, after all, UK crown dependencies or overseas territories – for massive economic advantage. And we're losing as a result. Is that appropriate at a time when we're all supposed to be "in this together"? And is this honest, at a time when large companies are currently the only part of the UK economy enjoying the prospect of tax cuts?

These big companies' tax rate will fall from 28% to 24% over the next four years – a move that seems generous, but quickly becomes ludicrous when it is appreciated that the effective tax rate of the largest companies in the UK is now 21%. This means that over the next four years, it is likely that their effective tax rate (that is, the rate they really pay) will fall to 17%. That's a lower tax rate than small companies will pay. It's lower than our VAT rate will be. It's also lower than our basic rate of income tax.

Is this tax justice? Is this "fairness"? Angry people, upset by the prospect of cuts for the poor and vulnerable in society, are rightly asking this question of what seems like a bastion of corporate privilege – the right not to pay the tax that the state should expect seems to be just that. If Osborne and his colleagues are to be credible, and if they are to persuade us the burden of tax is being shared fairly, then they have to tackle tax avoidance. This must be evidenced by scrapping all cuts at HMRC so the missing money is collected. And they must show us that they aren't giving favours to big business while denying the same ones to small UK companies and the rest of us alike.

As of right now, they're failing miserably to send out those messages. No wonder people are angry. They've got a right to be so.